CN105826438B - A kind of light emitting diode with metal buffer layer and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of semiconductors, and relates to a light-emitting diode with a metal buffer layer and a preparation method thereof, which at least includes a substrate, an AlN buffer layer and an epitaxial layer sequentially located on the substrate, and is characterized in that: the A metal buffer layer is also inserted between the AlN buffer layer and the epitaxial layer, and the metal buffer layer is composed of an Al particle layer and a Ni metal film layer, and the Ni metal film layer covers a plurality of Al particle surfaces to form a plurality of discontinuous The sheet structure exposes part of the bottom AlN buffer layer, and the epitaxial layer extends from the surface of the AlN buffer layer to the surface of the sheet structure. The epitaxial layer uses the metal buffer layer of the sheet structure as a mask to perform lateral epitaxial growth, so as to reduce the dislocation density of the epitaxial layer growth and prevent the extension of bottom defects.

Description

A light-emitting diode with a metal buffer layer and its preparation method

technical field

The invention belongs to the field of semiconductors, and in particular relates to a light-emitting diode with an Al/Ni metal buffer layer in a sheet structure and a preparation method thereof.

Background technique

In the LED manufacturing process, because it is very difficult to obtain single crystals of gallium nitride materials and the cost is high, gallium nitride materials are generally grown on heterogeneous substrates (sapphire, silicon carbide, silicon, etc.). Due to the large lattice mismatch (16%) and thermal expansion coefficient mismatch (34%) between GaN and sapphire substrates, a linear dislocation density of 10 ⁸ ~10 ¹⁰ cm ^-2 is generated in the GaN epitaxial layer, High dislocation density will affect the optical and electrical properties of epitaxial films. Therefore, growing materials on heterogeneous substrates needs to solve the nucleation problem between the substrate and the epitaxial layer. Due to the difference in lattice constant between materials, heteroepitaxy needs to be realized through a buffer layer. The buffer layer can relieve the lattice mismatch between the substrate and the epitaxial layer, and effectively improve the crystal quality of the epitaxial material. However, the existence of the buffer layer can only relieve a part of the lattice mismatch, and the actually grown GaN epitaxial material still has a relatively high density of dislocations.

The lateral epitaxial growth technology has obvious advantages in reducing the dislocation density, but the traditional lateral epitaxial growth requires the use of photolithography and other processes, which is complicated and costly.

Contents of the invention

In order to reduce the dislocation density of epitaxial growth, reduce defects, and simplify the lateral epitaxial growth process, the present invention inserts an Al/Ni metal buffer layer composed of a plurality of discontinuous sheet structures between the AlN buffer layer and the epitaxial layer, specifically The technical solution is as follows:

A light-emitting diode with a metal buffer layer, comprising at least a substrate and an AlN buffer layer and an epitaxial layer sequentially located on the substrate, characterized in that: a metal layer is inserted between the AlN buffer layer and the epitaxial layer A metal buffer layer composed of a plurality of discontinuously distributed sheet-like structures, the sheet-like structure is formed by alternating layers of Al particle layers and Ni metal film layers, and the AlN buffer layer exposed between adjacent sheet-like structures The layer is an AlN micro-region, and the epitaxial layer is located on the surface of the AlN micro-region and the sheet structure.

Preferably, in the metal buffer layer, the Al particle layer and the Ni metal layer are alternately stacked 2 to 20 times

Preferably, the metal buffer layer of the sheet structure has a regular or irregular shape.

Preferably, the metal buffer layer of the sheet structure is distributed uniformly or unevenly.

Preferably, the metal buffer layers of the sheet structures have the same or different areas.

Preferably, the metal buffer layer of the sheet structure has an area size ranging from 0.1 to 2×10 ⁵ nm ² .

Preferably, the particle diameter of the Al particle layer ranges from 1 to 5×10 ³ nm.

Preferably, the thickness of the Ni metal film layer is 0.5-10 nm.

The present invention also provides a method for manufacturing the above-mentioned light-emitting diode, comprising the following steps:

S1, providing a substrate;

S2, depositing an AlN buffer layer on the surface of the substrate;

S3. Prepare a metal buffer layer composed of a plurality of discontinuously distributed sheet-like structures on the AlN buffer layer, and the exposed AlN buffer layer between adjacent sheet-like structures is an AlN micro-region;

S4. Using the hydride vapor phase epitaxy technique to grow the epitaxial layer, wherein the growth of the epitaxial layer uses the sheet structure as a mask to selectively grow preferentially on the surface of the AlN micro-region, and then perform lateral epitaxial growth to extend to the surface of the sheet structure ;

Wherein, the specific growth steps of the sheet-like structure are as follows: firstly, the Al metal film layer and the Ni metal film layer are successively deposited on the surface of the AlN buffer layer by evaporation method; then, the Al metal film layer and the Ni metal film layer are repeatedly deposited Finally, the metal is melted at high temperature, and the temperature of the molten metal is controlled to melt the Al metal film layer to form an Al particle layer, while the Ni metal film layer breaks and covers a plurality of Al particles to form a sheet-like structure.

Preferably, the temperature range of the high-temperature melting is 550-1100 degrees.

Preferably, the Al metal film layer and the Ni metal film layer are repeatedly deposited 2 to 20 times.

The present invention has the following beneficial effects:

1) The metal buffer layer consists of a plurality of discontinuously distributed sheet-like structures, and the part of the exposed bottom AlN buffer layer between adjacent sheet-like structures is an AlN micro-region, and the growth of the subsequent epitaxial layer uses a plurality of sheet-like structures as a mask. The film is selectively and preferentially grown on the surface of the AlN micro-region, and then laterally epitaxially grown on the surface of the sheet structure, so as to realize the lateral growth of the epitaxial layer, further reduce the dislocation density of the epitaxial layer growth, and prevent the extension of the bottom defect;

2) The flaky structure is formed by alternate lamination of Al particle layers and Ni metal layers. Due to the reflective properties of metals, the reflectivity of light-emitting diodes can be further improved;

3) In the manufacturing method of the sheet structure, the melting point difference between Al metal and Ni metal is used to control the melting temperature, so that the Al metal film layer forms an Al particle layer, and since the melting point of Ni metal is higher than that of Al metal, the Ni metal film layer only increases with the melting point of Al metal. With the granulation of the Al metal film layer, it breaks and covers the surface of a plurality of Al particles, thereby forming a sheet structure, the process is simple, and no additional etching and other processes are required.

Description of drawings

FIG. 1 is a schematic diagram of a side view structure of a light emitting diode of the present invention.

Fig. 2 is a schematic top view structure diagram of the substrate, AlN buffer layer and metal buffer layer of the present invention.

Fig. 3 is a schematic side view of the sheet structure of the present invention.

FIG. 4 is a schematic flow chart of the manufacturing method of the light emitting diode of the present invention.

Fig. 5 is a schematic flow chart of the manufacturing method of the sheet-like structure of the present invention.

Drawings: 10. Substrate; 20. AlN buffer layer; 21. AlN micro-region; 30. Sheet structure; 31'. Al metal film layer; 31. Al particle layer; 32. Ni metal film layer; 40. epitaxial layer.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings of the present invention all adopt very simplified and inaccurate scales, which are only used to facilitate and clearly illustrate the present invention.

Referring to accompanying drawing 1, the present invention discloses a light-emitting diode with a metal buffer layer, at least comprising a substrate 10 and an AlN buffer layer 20 and an epitaxial layer 40 sequentially positioned on the substrate 10, wherein the AlN buffer layer 20 and the epitaxial layer A metal buffer layer composed of a plurality of discontinuously distributed sheet-like structures 30 is also inserted between the 40, the exposed bottom AlN buffer layer 20 between adjacent sheet-like structures 30 is the AlN micro-region 21, and the epitaxial layer 40 is located on the AlN micro-region 21 surface and sheet structure 30 surface. The substrate 10 can be a flat substrate or a patterned substrate, and the material can be silicon, silicon carbide, sapphire and the like. The epitaxial layer 40 uses the discontinuously distributed sheet-like structure 30 as a mask for epitaxial growth, and the epitaxial layer 40 grows selectively and preferentially on the surface of the AlN micro-region 21, and then grows laterally, extending from the surface of the AlN micro-region 21 to the sheet-like structure On the surface of 30, during lateral epitaxial growth, on the one hand, the mask blocks the defects at the bottom from extending upwards; on the other hand, the defects grow from the AlN micro-region 21 to the surface of the sheet structure 30, thereby reducing the defects in the growth of the epitaxial layer 40.

Referring to FIG. 2 , the sheet-like structures 30 can be in regular or irregular shape, evenly distributed or unevenly distributed, and have the same or different areas. In order to achieve the optimal effect of reducing growth defects, in this embodiment, the lamellar structures 30 are preferably irregular in shape, unevenly distributed, and have different areas, and the area size ranges from 0.1 to 2×10 ⁵ nm ² .

Referring to Fig. 3, the sheet-like structure 30 is formed by alternating layers of Al particle layers 31 and Ni metal film layers 32 periodically, wherein the Ni metal film layer 32 covers the surface of a plurality of Al particles to form a sheet-like structure. Al particle layers 31 and Ni metal film layers 32 are stacked alternately for 2-20 times. Wherein, the thickness of the Ni metal film layer 32 is 0.5-10 nm, and the particle diameter range of the Al particle layer 31 is 1-5×10 ³ nm.

In the present invention, a metal buffer layer composed of a plurality of discontinuously distributed sheet-like structures 30 is added between the AlN buffer layer 20 and the epitaxial layer 40, and the sheet-like structures 30 are formed by alternately stacking Al particle layers 31 and Ni metal film layers 32 , the AlN buffer layer 20 at the bottom is exposed between adjacent sheet-like structures 30 to form AlN micro-regions 21. In the subsequent process of growing the epitaxial layer 40 by hydride vapor phase epitaxy, due to the The lattice difference of AlN is relatively large, and the growth of the epitaxial layer 40 uses the sheet structure 30 as a mask to selectively preferentially perform epitaxial growth on the surface of the AlN micro-region 21, and then extend to the surface of the sheet structure 30 for lateral epitaxial growth. During the epitaxial growth process, since the flake structure 30 serves as a mask to block the upward extension of the underlying defects, the defects bend and extend from the AlN micro-region 21 to the adjacent flake structures 30 on both sides, thereby reducing the growth dislocation density of the epitaxial layer 40 , reducing growth defects. At the same time, the sheet structure 30 is composed of Al and Ni metals, which has higher reflectivity and improves the luminous effect of the light emitting diode.

Referring to accompanying drawing 4, in order to prepare above-mentioned light-emitting diode, the present invention also provides a kind of manufacturing method, comprises the following steps:

S1, providing a substrate 10;

S2. Deposit an AlN buffer layer 20 on the surface of the substrate 10; the AlN buffer layer 20 can be deposited by PVD or MOCVD;

S3. Prepare a metal buffer layer composed of a plurality of discontinuously distributed sheet-like structures 30 on the AlN buffer layer 20, and the exposed AlN buffer layer 20 between adjacent sheet-like structures 30 is an AlN micro-region 21;

S4. Using the hydride vapor phase epitaxy technique to grow the epitaxial layer 40, wherein the growth of the epitaxial layer 40 is selectively and preferentially grown on the surface of the AlN micro-region 21 using the sheet structure 30 as a mask, and then the lateral epitaxial growth is performed to extend to the sheet structure 30 surface.

Referring to accompanying drawing 5, wherein the specific growth steps of sheet-like structure 30 are: first, deposit Al metal film layer 31 ' and Ni metal film layer 32 successively on the surface of AlN buffer layer 20 by vapor deposition; then, repeatedly deposit Al metal film Layer 31' and Ni metal film layer 32 have a cycle number of 2 to 20; finally, high-temperature molten metal is controlled at a temperature of 550 to 1100 degrees to melt the Al metal film layer 31' into an Al particle layer 31, while the Ni metal film The layer 32 breaks and covers the surface of the plurality of Al particles to form a sheet structure 30 .

In the manufacturing method of the sheet structure 30, the melting point difference between Al metal and Ni metal is used to control the melting temperature, so that the Al metal film layer 31' forms the Al particle layer 31, and because the melting point of Ni metal is higher than that of Al metal, the Ni metal film layer 32 only breaks and covers the surface of a plurality of Al particles, thereby forming a sheet-like structure 30, the process is simple, and no additional etching and other processes are required. It should be understood that the above specific implementation is a preferred embodiment of the present invention, the scope of the present invention is not limited to this embodiment, and any changes made according to the present invention are within the protection scope of the present invention.

Claims (11)

1. A light-emitting diode with a metal buffer layer, at least comprising a substrate and an AlN buffer layer and an epitaxial layer positioned on the substrate successively, characterized in that: also inserted between the AlN buffer layer and the epitaxial layer A metal buffer layer composed of a plurality of discontinuously distributed sheet-like structures, the sheet-like structures are formed by periodically alternately stacking Al particle layers and Ni metal film layers, and the exposed parts between adjacent sheet-like structures The AlN buffer layer is an AlN micro-region, and the epitaxial layer is located on the surface of the AlN micro-region and the sheet structure. 2. A light-emitting diode with a metal buffer layer according to claim 1, characterized in that: Al particle layers and Ni metal film layers are alternately stacked 2 to 20 times in the sheet-like structure. 3. A light-emitting diode with a metal buffer layer according to claim 1, wherein the sheet-like structure is in a regular or irregular shape. 4. A light-emitting diode with a metal buffer layer according to claim 1, wherein the plurality of sheet-like structures are distributed uniformly or unevenly. 5. A light-emitting diode with a metal buffer layer according to claim 1, characterized in that the areas of the plurality of sheet structures are the same or different. 6. A light-emitting diode with a metal buffer layer according to claim 1, characterized in that: the area of the sheet-like structure ranges from 0.1 to 2×10 ⁵ nm ² . 7. A light-emitting diode with a metal buffer layer according to claim 1, characterized in that: the particle diameter of the Al particle layer ranges from 1 to 5×10 ³ nm. 8. A light-emitting diode with a metal buffer layer according to claim 1, characterized in that: the thickness of the Ni metal film layer is 0.5-10 nm. 9. A method for making a light-emitting diode with a metal buffer layer, comprising the steps of: S1, providing a substrate; S2, depositing an AlN buffer layer on the surface of the substrate; S3. Prepare a metal buffer layer consisting of a plurality of discontinuously distributed sheet-like structures on the AlN buffer layer, and the exposed AlN buffer layer between adjacent sheet-like structures is an AlN micro-region; S4. Using the hydride vapor phase epitaxy technique to grow an epitaxial layer, wherein the epitaxial layer selectively grows preferentially on the surface of the AlN micro-region using the sheet structure as a mask, and then performs lateral epitaxial growth to extend to the surface of the sheet structure; The forming steps of the sheet-like structure are as follows: firstly, the Al metal film layer and the Ni metal film layer are successively deposited on the surface of the AlN buffer layer by evaporation method; then, the Al metal film layer and the Ni metal layer are deposited repeatedly for several times; Finally, the metal is melted at high temperature, and the temperature of the molten metal is controlled to melt the Al metal film layer to form an Al particle layer, while the Ni metal film layer breaks and covers a plurality of Al particles to form a sheet structure. 10 . The method for manufacturing a light-emitting diode with a metal buffer layer according to claim 9 , wherein the temperature range of the high-temperature melting is 550-1100° C. 11 . 11. The method for manufacturing a light-emitting diode with a metal buffer layer according to claim 9, characterized in that: the Al metal film layer and the Ni metal film layer are repeatedly deposited 2 to 20 times.